Conventionally, in a manufacturing process for a semiconductor device or the like, a microscopic circuit pattern has been formed by performing an etching process, e.g., a plasma etching process on a substrate such as a semiconductor wafer. In this etching process, a mask is formed by a photolithography process employing a photoresist.
With respect to this photolithography process, there have been developed various techniques so as to keep up with the miniaturization of a pattern to be formed. One example is so-called a double patterning. In the double patterning, a two-step patterning is performed in one step, a first pattern is formed by a first lithography process of performing coating, exposure and development processes on a photoresist; and in the other step, a second pattern is formed by a second lithography process of performing coating, exposure and development processes again on a photoresist after the first lithography process. By performing the two-step patterning, it is possible to form a mask having a finer gap in comparison to a mask formed by performing the patterning only once (for example, see Patent Document 1).    Patent Document 1: U.S. Pat. No. 7,064,078